Palynofloras of the Kocaçay and Cumaovası basins in western Turkey that belong to a time-span from the late Early to late Middle Miocene (the late Burdigalian-Serravallian) are studied and compared with published palynofloras of Europe and Turkey. Palynological data and numerical climatic results obtained by the coexistence approach indicate palaeoclimate changed from warm subtropical to temperate during the late Burdigalian-Serravallian. Moreover, the palaeoclimates of the Kocaçay and Cumaovası basins are compared with continental palaeoclimatic records of coal-bearing sediments in western Turkey and current temperatures in the İzmir region. According to this comparison, palaeoclimatic results of these basins and other localities in western Turkey show a distinct difference as a result of orographic change. The palaeovegetation in the Kocaçay and Cumaovası basins during the studied time-span was affected by palaeotopography and palaeoclimate. In these basins mixed mesophytic, coniferous forests, and swamp palaeovegetation generally predominated during the late Early-early Middle Miocene. The role of the herbaceous taxa increased at the end of the late Middle Miocene (the Serravallian) in the Kocaçay and Cumaovası basins. It is obvious from the palynomorph data of these basins that grassland palaeovegetation started to expand in the late Middle Miocene. Unlike in Central Europe, where late Burdigalian and Langhian represent a period of outstanding warmth, the so-called Mid-Miocene Climatic Optimum, cold month mean temperatures reconstructed in this study point to an ongoing cooling trend, already from the late Burdigalian onwards, possibly related to increasing terrestrial conditions in the study area.
The Bolvadin Fault, which forms one of the northern boundaries of the Afyon Akşehir Graben, creeps aseismically on the surface of earth and has not generated surface-rupture earthquakes during instrumental time. Our geological mapping and palaeoseismological studies reveal that the Bolvadin Fault is an approximately 2 km wide and 16 km long, dip-slip normal fault. It could generate earthquakes up to Mw 6.48 roughly every 1 ka and the latest surface-rupture event (M > 6) occurred 494 ± 45 years ago on the Bolvadin Fault. The throw over the past 5 Ma is measured as approximately 500 m according to relative positions of the basal unconformity of Pliocene clastics on both sides of the fault yielding a long-term average slip rate of 0.1 mm/year. Palaeoseismic trenching at two sites on the Bolvadin Fault document that the fault was reactivated by at least two linear morphogenic earthquakes during the past 2570 years. They probably occurred in 530 (AD) and 1525 ± 45 (AD). We also determined a mean late Holocene slip rate of about 0.64 mm/year at trench 1. Palaeoseismic data suggests that aseismic surface deformations (postseismic relaxation) which began developing after the 2002 Çay earthquakes (Mw: 6.3 and 6.0) follows the older surface rupture of the Bolvadin Fault.
Anadolu’nun Neotektonik dönemi yapılarından biri olan Doğu Anadolu Fay Zonu (DAFZ) kıta içi deformasyonu sağlayan sol yanal doğrultu atımlı aktif bir fay zonudur. DAFZ; kuzey kol ve ana kol olarak da adlandırılan güney kol olmak üzere iki bölümden oluşmaktadır. Bu çalışmanın konusunu DAFZ’nin güney kolu üzerinde meydana gelen 6 Şubat 2023 Pazarcık depreminde (Mw: 7,7), Erkenek Segmenti üzerinde gelişen yüzey kırığının Çelikhan (Adıyaman) yakınlarındaki bölümü üzerinde gerçekleştirilen detaylı jeolojik, paleosismolojik ve haritalama çalışmalarının ön bulguları oluşturmaktadır. Yapılan çalışmalarda yüzey kırığı Çelikhan kesiminde 50 cm düşey atımın eşlik ettiği maksimum sol yanal yer değiştirme miktarı 3,25 m olarak ölçülmüştür. Çelikhan’ın kuzeydoğusuna doğru gidildikçe sol yanal yer değiştirme miktarının azaldığı ve sönümlendiği görülmüştür. Erkenek segmenti boyunca fay düzlemlerinden ölçülen kayma verilerinin kinematik analizi sonucunda, segmentin geometrisi ile uyumlu deformasyonun yaklaşık KD-GB ve KKB-GGD doğrultulu sıkışma gerilmesiyle ilişkili doğrultu atımlı tektonik rejim altında geliştiği saptanmıştır.
The output (.pmag) file including details of paleomagnetic analysis performed in this study can be evaluated and visualized in the available modules of the online portal of Paleomagnetism.org.
In West Anatolia near the cities of İzmir and Manisa, the historical occurrence of large earthquakes suggests the presence of important seismogenic faults. However, these faults have yet to be investigated in detail. The Manisa Fault Zone (MFZ) is an active large-scale normal fault system in this area, and thus field observations and palaeoseismological studies of this zone are important for predicting future earthquakes. Hence we sought to document geological and palaeoseismological evidence for Holocene activity on the MFZ. We performed trenching to determine the magnitude and timing of past surface-faulting events using detailed fault-trace mapping, measurements of Upper Pleistocene-Lower Holocene sediments, and radiocarbon dating. By comparing the trench data with palaeoearthquake records, we find evidence for three palaeoearthquakes which correspond to 926 AD, 1595 or 1664 AD, with the most recent event in 1845 AD. We also find this in the central and western sectors of the MFZ, which together with the eastern sector comprise the three major seismogenic zones. The Pliocene-Quaternary vertical offset at fault scarps is far less than that in the western sector, suggesting that activities of these sectors are highly independent. Evaluation of field observations suggests that the MFZ has been the source of multiple Late Pleistocene and Holocene surface-rupturing earthquakes. Our results constitute the first palaeoseismic evidence on the causative faults of historical earthquakes that affected Manisa, and point to their underlying tectonic mechanisms.
